DISCOVER THE UNIVERSE
DISCOVER THE UNIVERSE AST 1002
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Ms. Adrian Buckridge
verified elite notetaker
Popular in Astronomy
Ms. Adrian Buckridge
verified elite notetaker
This 12 page Study Guide was uploaded by Ms. Adrian Buckridge on Friday September 18, 2015. The Study Guide belongs to AST 1002 at University of Florida taught by Staff in Fall. Since its upload, it has received 27 views. For similar materials see /class/206979/ast-1002-university-of-florida in Astronomy at University of Florida.
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Date Created: 09/18/15
AST 39 Topic D Parl3 Page I y Three Basic Types of Spectra See Study Guide Figure sc Toplc D Described by 915m Klmhnquot 1859 Gemini phwunnm 4m Par 3 TYPEs 39 sperm Types nllen glvm as 39lhvee laws39 Kircho 39s Law War Version nlnsr IA 39nur h quotpg ab knnwquot Types of Spectraquot Types of Spectraquot 1 Gnrllnums 9pm 2 Em a u x 3 Ahsnvrllnn armhune I Emlsslnn le m Gnrllnmus m 9 What arelhe hlee pnysmzlslxms l its J wmmm I I ust Mm u The 39 39 r ain EXAMPLES quot Snlld 390 7 was at Liquid I Mum I mum m 19 Gas mum emquot m him a Dmsegas curpa 02m in 01m m nansm AST 39 Topic D Perl 3 Page 2 ustq m Em s on Line Spectra A Box of Air m nmmuw fnm mwr mm myymm mmmms Reduce Pressure Air at Low Pressure ham Sum m ham In my 4 H m a Fingerprints of the Elements Spectral Bands m summte has zurlque unlsslm line palm 50mm quot5 my We P tunxie39lyliwr armgme um Spectral hands wldespe lal Ilnes Pennixmumci mum m IDFI Il i WHEN m curpa 02m in 01m m nansm Topic D Perl 3 Page 3 rm 3 z mum me IyIn in mm wlmzx Comparison Spectra Absorption L Amnomu umily all m m namxpmm z menus um mm a haml Fingerprints Again The Solar Spectrum m an v leeunlsslmspumz W waywarpr m J m W a p aWi gu men 5417 w 339 Sinn Wimim 7m le nW39Tquot NEW quot umEe quotmaquotan quot Minimum 1 mm gem in m mugum m Emission on Continuou envynoun in mm Basic Structure of Stars I151 stars shun msovpnnn llnespmm 0mmquot Sm mmsmsmyuuaanswssmmm m nansm AST 1002 Slide Handouts Topic D Part 3 Page 4 What Can You Conclude Continuous spectrum gt Star Hot dense gas What Can You Conclude Continuous spectrum gt Star Hot dense gas Dark lines Igtln front cooler rarefied gas Dark lines gtln front cooler rarefied gas But is this correct Hot Probably not Dense Gas WhY star Answer IS 41 An swe r Wham Continuous spectrum gt Star Hot dense gas Dark lines Igtln front cooler rarefied gas More likely Hot 1 Dense Gas Star 5 Copyright 0 2001 HL Cohen Ver 030601 AST 1002 Slide Handouts Topic D Part 5 Page 1 ltOgt Topic D Part 5 Radiation Lawsquot Web Version 030601 Continuous Spectra Importance amp Uses Continuous Spectra Appearance What cannot do chemical identification Why a What can do obtain temperatures of objects Real Stellar Spectra Usually show dark lines w Also show a continuum m 39 A temperature indicator Radiation Three laws characterize continuous spectra Listed in Study Guide Fig 7 Planck Wien StefanBoltzmann Why important Can determine temperature I See Fig7 Laws A Note Black and White Stars show this Bul spectrograms usually not in color BIW easy to produce Get used to this HlJIIl Graph results Ii Radiation Curves Stellar spectra look like Measure intensity brightness Absar ianLine ectrum from end to end with light meter39 Intensity Wavel en gth Eu continuunuugunuuuuuuug 9 g 9 a E a 39139 m E ra iat n curve39 nuvelengm 6 Copyright 0 2001 HL Cohen Ver 030601 AST 1002 Slide Handouts Topic D Part 5 Page 2 Dips Show Lines Abs Lianine ggectnn Stellar spectra look like Measureintensity brightness from end to end Erase Lines Continua us estmm from graph Looks like a continuous spectrumj lf erase lines with light meter39 5 N ana39yze as 5 39g If spectrum has 39g Graph result 2 no lines 2 without lines quotavalalluul 7 quotavalalluul 8 Perfect Radiators Cool Black Bodies Invent idealized radiator39 Often called a black body BB Simplifies understanding of radiation Continuous S ectrum Stellar radiation curves lines erased often 39 resemble BB s ty lntens to simulate stars Use BB radiation curves At room temperature Absorb allincoming radiation Radiate back all radiation received Then why look black Answer Most radiation emitted in 7 Hot Black Bodies Substantial Heat Black Body Visible Sn Absorbs allincoming radiation In 0quot Radiates back all radiation received Nowlooks bright why Answer Signi cant radiation emitted in 7 The Radiation Laws Three laws characterize continuous spectra Planck Wien StefanBoltzmann Listed in Study Guide FIg 7 Copyright 0 2001 HL Cohen Ver 030601 AST 1002 Slide Handouts Topic D Part 5 Page 3 See Fig 7 See Fig 7 Recall the Radlatlon C Recall the Radlatlon C 10 10 Not to scale N01 to scale 08 08 g 0396 This is a radiation curve of a black body I E 04 Equation of curve is Planck s law39 I g I It is a general description of how black bodies radiate 02 02 l E I 00 00 on uv VIBGYOR IR wwnw aux uv VIBGYOR IR MNRW Warelenglh Wavelength I3 l4 Characteristics of BB Cu rves Black Body Radiation Curves 10 10 Not to scale N01 to scale 08 Single Pedr Know this 08 g 0396 l 30 know 2 0396 If temperature changes curve changes 04 0 quot Rises cum F IIS 135535 04 Planck39s Law also shows how a I a 02 quot4 02 Asymptote 00 00 R ThIs Is Planck s Law In graphical form w 3m W V a Gv 0R IR MN Rw are engl Wavelength l5 l6 Th ree Temperatu res Temperatu re amp BB Cu rves 10 10 Not to scale N01 to scale I gt 0398 gt 0398 th 2things occur astemp ris l 05 How do these curves differ 06 1 7 E Remaining two radiation laws detail this E g 04 Honest g 04 Honest 2 7 E E 02 02 V TM39 MdRange Coolest 00 mm 00 a Rm uv VIBGYOR MNRW 3am uv VIBGYOR IR MNRW Warelenglh Wavelength l7 l8 Copyright 0 2001 HL Cohen Ver 030601 To pic D Perl 5 Page 4 Thvee laws chamclenze mmmunus spema Second Radiation Law Nn nexs un uil u may mmm it Am magnum n mob Second Radiation Law Wein s Law n Three laws chamclenze mmmunus speclva g j m m mnmwmnm i In Peak mm tnzl menu i i mm Warm 392 i Puik m an IR m min um m a Thvee laws cham Second Radiation Law enze mmmunus spema Generil sauna m ni nn A Consequence Rm In unbilmnnniaummummrmnnni nsequmc imppnselenuemlure m 9m 4mm x Mm envynoun in mm In nansm AST 1002 Slide Handouts Topic D Part 5 Page 5 A Consequence Examples Conclusion Stars with more than about Sirius twice or onehalf of Sun s temperature 121000 K have radiation peaks in Benign UV or IR respectively I32 IR UV Second Radiation Law Example of Wein s Law See Study Guide Example Worked Problem 3 Third Radiation Law Total Energy Radiated Let Erm Total energy radiated 10 Not to scale 08 Star As temperdure rises curve ER 1 over elm specm m g 05 becomes higherateverywavelength 2 Through some area E Sototal energy radiated over entire Y a square meter E 04 WNWquot quotW Greater 1 sq in Not from whole star 3935 02 So star s radius irrelevant 00 mm 39 Rm W W B G W IR MN Rw then where T Temperature Walelenglh 27 28 See Fig 7 Summary Radlatlon Llaws Here 5 How It Works Three laws characterize continuous spectra 5 A n 121000K I m mmm St a TB 6000K f Planck General description of radiation thequot quotSeriales emi Wlen Peak shifts toward shorter wave can ndhnw lengths if Tincreased WLPkoc 1 T StefanBoltzmann Total energy radiated over entire spectrum increases if Tincreased ET01 o T utes Emma 6000 K 14 1 compare 29 See Study Guide Example 4 Copyright 0 2001 HL Cohen Ver 030601 AST 39 Topic D Perl 5 Page 6 A Few Examples Color of the Sun Cnmmnn nhlu s Illuslvdelhe vadlallnn laws 0 Celesllalhndles awenanunhu 1 Hnusehnld Ilerrs O The Solar Impression So Color of the Sun TJSSZFTquot O O O O See Star Colors for Yourself u mm m Munmmnnyel39 Drier VHF mm m ragaMew Mm Mama I curpa om m 01m m nansm AST 1002 Slide Handouts Topic D Part 5 Page 7 Wien s Law and Color Watch a Stove Burner Heat a H at Changing color of many hot objects a mum only pm quotmar e s consequence of Wien s Law nfreflected mm Iigm Results from a shifting disfribufionof color 6 e Off Dull Red OrangeRed Bright Orange Everyone has experienced Wien s Law Wsible lighl Color Ghmge Burner does not Watch a stove bumer heat and change color salable WIHI S LEW ecome hol enou or heating element or light bulb filament moi rgdl lllon Increasing Bright39s 0 ShOqunhel39 enquot 6 as R St anBollznann 37 38 Light Bulb on Dimmer Switch Side Note Planck s Law FilamentHeats Many tried to find equation for BB curve That is a relation between a rs n 7 39 Intensity II I Wavelength Temperature V V v v v M Duquot Dim an Brilliant Early atttempts failed examplefollows Red Ormge Yellow YellowWhite 39 4 Example of Early Attempt Why Planck Succeeded 10 N n l 08 Nquot LIke Kepler threw away old Ideas gt 39 arlier attempts to nd an equation failed g 05 ml Previously E Radiation visualized as water flowing g 04 The uvcatas PM Wmquot 395 quotmamquot continuously from a hose C quot quotquot quot5 E f of this curve Flow 02 Success dueto new 00 hypothesis about radiation I Rm UV VI 3 av 0R IR MN RW Recall Kepler did same for celestial motions Walelenglh M 42 Ver 030601 Copyright 0 2001 HL Cohen AST 1002 Slide Handouts Topic D Part 5 Page 8 What Planck Did What Resulted Planck postulated Planck derives equation fitting black body curves Radiation bundled into particles of energy I znhc 2 Energy packets called photons QQQ a A Radiation spurts like water Thom from a spray bottle or water gun DD quotM Mquot to know quotquot5 H Each spurt39 or packet39 Today BBs sometimes called Planck radiators like a photon 39 4 44 Copyright 0 2001 HL Cohen Ver 030601
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